1. Field of the Invention
The present invention relates to a rubber part having an aluminum-based metal component such as a bushing and an engine mount for automobiles, and a vibration damping member for industrial machinery, and a method of producing the same.
2. Description of the Art
In recent years, a rubber part having an aluminum-based metal component, which is formed by integrating the metal component and the rubber part to be used as a connecting member between various components of a frame or an engine, has been used as bushings and engine mounts for automobiles, and vibration damping members for industrial machinery.
The rubber part having an aluminum-based metal component has a problem that corrosion on a surface of the metal component on an interface between the rubber part and the metal component causes separation therebetween, leading to a deterioration of the function of the rubber part having an aluminum-based metal component. For preventing the corrosion, the surface of the metal component is generally subjected to chromate treatment to form a chromate-based chemical film on the surface as disclosed in, for example, Japanese Unexamined Patent Publication No. 6-179978.
However, since crystallization water contained within the film structure of the chromate-based chemical film is easily dehydrated by heat generated during vulcanization of rubber, the film is vulnerable to cracks because of contraction of the film and to deterioration of adhesiveness. If a metal component under this condition is processed for diameter reduction or the like, the film may be unable to transform following the squeezing of the metal component, and cracks may be formed in the film, which leads to deterioration of adhesiveness between the metal component and the rubber part and insufficient protection of the metal component against corrosion.
In view of the foregoing, it is an object of the present invention to provide a rubber part having an aluminum-based metal component provided with a chemical film formed on the surface of the metal component, which is capable of transforming following the squeezing of the metal component, and a method of producing the same.